In manufacturing engines mounted to a vehicle and an outboard motor, the engines having identical basic specifications are sometimes modified to have maximum horsepower and output characteristics so as to meet regulations on exhaust gas and maximum speed in destinations. For example, as a common method for modifying the maximum horsepower of the engine, there has been a process that restricts maximum engine speed of the engine and a process that restricts an ignition timing, fuel injection quantity, or air-intake volume. These processes are controlled based on programs stored in engine control devices. Accordingly, there has been a problem that a user illegally installs an engine control device that stores a high output program to an engine manufactured for low output, thus the engine is modified to a high-power engine. In this case, the engine fails to meet the regulations in the destination.
Japanese Laid-open Patent Publication No. 11-82146 discloses an engine model discrimination device that performs an operation comparing a pulse signal, which is unique to a gear having different number of teeth by each engine model, with the preliminarily recorded number of teeth, so as to discriminate the engine model. The engine model discrimination device of Patent Document 1 selects and executes an engine control program appropriate for the discriminated engine model after discriminating the engine model based on the operation result.
The engine model discrimination device of Japanese Laid-open Patent Publication No. 11-82146 is employed to ensure preventing or reducing the modification by replacing the engine model discrimination device. However, the engine model discrimination device of Japanese Laid-open Patent Publication No. 11-82146 is originally required to store a plurality of programs corresponding to the number of the engine models other than the necessary programs. Therefore, storage capacity requires to be ensured more than necessary for storing the programs, thus engine cost increases as the number of the engine models increases. Accordingly, for cost reduction, it is necessary to store the programs corresponding to the engine model to decrease the storage capacity. Thus, in Japanese Laid-open Patent Publication No. 11-82146, the cost reduction and the prevention of the engine modification are incompatible.